1. Field of the Invention
This invention relates to compositions and methods for protecting plants from damage due to exposure to cold but non-freezing temperatures (chilling temperatures). Furthermore, this invention relates to compositions and methods to help plants recover from chilling injuries.
2. Description of the Prior Art
Chilling injury is a term used to describe the physiological damage that occurs in many plants and plant commodities as a result of exposure to a chilling temperature. Such injuries lead to significant destruction of produce quality and quantities, delay in growing, blooming and fruit bearing, and in the worst case, destroying and killing the plants exposed. For example, in the far east oriental countries, more often than not, early spring chill has been the major cause of reduction in rice production. The result is a concomittant financial loss for producers, processors and consumers.
Unlike a frost (freezing) injury, the chilling injury of plants may not be detected immediately after the exposure to the chilling temperature. The belay in showing an injury symptom is the reason why not many statistical damage reports are available to demonstrate how serious the chilling injury can be. However, such injuries will affect plants in growing and bearing fruit, as illustrated in the examples hereafter.
There is no single unifying theory to explain the mechanism of chilling injury development in fruits and vegetables. This is not surprising, considering the diversity of botanical structure of various fruits and vegetables and the ramifications of the variety of chilling injury symptoms. However, efforts by numerous researchers working on chilling injury during the last two decades have greatly increased understanding about the response of plants to chilling temperatures. Several events have been demonstrated to occur instantaneously in the chilling-sensitive tissues upon exposure to chilling temperatures. These events include a change in membrane lipid structure, a conformational change in some regulatory enzymes, an alteration in cytoskeletal structure, and an increase in the concentration of cytosolic calcium.
Several methods have shown promise in alleviating chilling injury. These methods include temperature preconditioning, intermittent warming, controlled atmosphere storage, chemical treatments, hormonal regulations, and genetic modification. However, a method or composition which would stop or help treat chilling injury, or which would transform plants from being chilling-sensitive to chilling-resistant, has not been found.